BIOSCIENCE: DES With Biodegradable Polymer Matches Comparator

Marlene Busko

September 02, 2014

BARCELONA, SPAIN — One year results from the BIOSCIENCE study showed that an innovative stent with thinner-than-usual struts and a biodegradable polymer coating that releases the antiproliferative drug sirolimus within two years and then disappears is as safe and effective as a current gold-standard stent[1].

The ultrathin-strut, biodegradable-polymer sirolimus-eluting stent (Orsiro, Biotronik) was not inferior to the durable polymer everolimus-eluting stent (Xience Prime/Xpedition, Abbott Laboratories) for the primary end point of target lesion failure—cardiac death, target vessel MI, or clinically indicated target vessel revascularization.

Dr Thomas Pilgrim (Swiss Cardiovascular Center, University Hospital, Bern, Switzerland) presented the trial results here at the European Society of Cardiology 2014 Congress , and the results were simultaneously published in the Lancet.

Commenting to heartwire following a press conference, Pilgrim said, "This novel stent matches the results of the best-in-class drug-eluting stent that we have right now [and] had an excellent safety profile." At one year, target lesion failure had occurred in 69 cases (6.5%) with the experimental stent vs 70 cases (6.6%) with the comparator (p for non-inferiority <0.0004).

Press conference co-chair Dr Jens Christian Gerdes (Aarhus University Hospital, Denmark) told heartwire that this was a well-performed study, but long-term results at two, three, and five years will be of interest.

In an editorial accompanying the article[2], Drs Julinda Mehilli and Steffen Massberg (Munich University Clinic and Ludwig-Maximilians University, Germany) praise the trial design but point out that the trial used a wide range (3.5%) to define noninferiority. "It seems that, with the newer generations, the maximum reduction in adverse events achievable by metallic-scaffold improvement has already been reached," they write, adding that perhaps research efforts should shift to biodegradable stents.

The Case of the Vanishing Polymer

Dr Thomas Pilgrim

With continuing enhancements in stent design, strut thickness, and polymer coatings, outcomes after PCI have greatly improved, the researchers write. Biodegradable polymers were introduced to overcome concerns that delayed arterial healing might lead to very late stent thrombosis and restenosis, they add.

BIOSCIENCE aimed to compare the novel biodegradable polymer sirolimus-eluting stent with the standard of care—a thin-strut durable polymer everolimus-eluting stent—in a large "all-comers" patient population.

The two stents have the same platform material—cobalt chromium, L-605. But the newer stent has thinner struts (60 µm vs 81 µm), and it also has a passive silicone carbide layer (to reduce the interaction between the bare-metal stent and surrounding tissue).

From 2012 to 2013, the researchers enrolled 2119 patients (with 3139 lesions) who had coronary artery disease and were undergoing PCI in nine centers in Switzerland. About one in five patients presented with STEMI.

The patients were randomized to receive the novel stent (1063 patients; 1594 lesions) or the comparator stent (1056 patients; 1545 lesions).

There were no differences in the primary end point, the components of the primary end point, or for patients stratified based on gender, diabetes, acute coronary syndrome, renal failure, or off-label use.

In the 20% of patients in the trial who had STEMI, target lesion failure occurred in only 3.3% of cases where the new stent was implanted vs 8.7% of cases where the comparator stent was implanted (relative risk 0.38, p=0.024). However, since the study was not powered to assess this subgroup of patients—who are at highest risk from ischemic adverse events—further study of this is needed, Pilgrim said.

Editorialists Call for Research into Disappearing Stents

Mehilli and Massberg note that "although almost 250 000 patients were enrolled in [recent] trials, the difference in outcomes between test and comparator drug-eluting stent platforms is low (less than 1.5%). This difference emphasizes the excellent performance of the drug-eluting stent platforms on the market and, on the other hand, questions the necessity for newer drug-eluting stents."

Thus, "the large body of accumulated scientific evidence, including the important results from BIOSCIENCE, should trigger research efforts and economic resources to focus on functional restoration of the stented coronary artery—for example, with fully bioresorbable vascular scaffolds," they conclude.

As Gerdes commented: "From a patient's perspective, if I had to have a stent, I would like one that disappeared. . . . If the stent has done its, job why not make it disappear?"

Pilgrim has received travel expenses and payment for lectures from Biotronik. Disclosures for the coauthors are listed in the article. Mehilli has received speaker's fees from Abbott Vascular, Biotronik, Lilly/Daiichi, Sankyo, and Terumo. Massberg declares no competing interests.

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